Increase In Load Carrying Capacity Research Articles

Tribological and Chemical–Physical Behavior of a Novel Palm Grease Blended with Zinc Oxide and Reduced Graphene Oxide Nano-Additives

The role of industrial lubricants in machinery is to reduce friction and wear between moving components. Due to the United Nations’ tendency to reduce dependency on fossil fuel, a general awareness is strongly driven towards developing more eco-friendly lubricants. Palm oil possesses promising properties, which promote it to be a competitive alternative to the hostile mineral oils. Still, marginal oxidation stability, viscosity, and tribological properties remain critical issues for performance improvement. This paper presents an improved palm grease using reduced graphene oxide (rGO) and zinc oxide (ZnO) nano-additives at different concentrations. Oil and grease samples were tested for viscosity, oxidation stability, pour point, penetration, roll stability, dropping point, churned grease-oil release, copper corrosion, friction, and wear. ZnO additives enhanced the oxidation stability by 60% and shifted the pour point to 6 °C. Adding ZnO and rGO to the palm grease increased the load-carrying capacity between 30% and 60%, respectively, and reduced the friction coefficient by up to 60%. From the wear scar morphologies, it is believed that graphene 2D nanoparticles formed absorption layers which contributed to the increase in load-carrying capacity, while ZnO chemically reacted with the metallic surface layer, forming zinc compounds that resulted in a protective boundary lubricating film.

Experimental Study Of Simple Cyclic Testing On Reinforced Beam Using Fiber Reinforced Polymers (FRP)

The geographical location of Indonesia on the Ring of Fire makes it prone to earthquakes. Frequent earthquakes cause failures in construction. Construction failures must be repaired to restore the strength of the structures to their original or even higher levels. One type of structural reinforcement is Fiber Reinforced Polymers (FRP). FRP can enhance the strength of beams damaged by earthquakes, alter the structural failure mode, increase load-carrying capacity, and prolong plastic hinges in beam elements. This study recommends using FRP to reinforce concrete structures, particularly beams. The first stage of the research involves experimental testing on a prototype not wrapped with FRP. After reaching peak strength and experiencing failure, then the prototype is covered with FRP. Subsequently, the prototype is retested until it gets peak strength and experiences failure again. Both specimens are subjected to monotonic loading, which is simulated as cyclic loading. Data processing is performed by analyzing the results of the experimental testing on both prototypes. The processed data includes crack patterns in the beams, cyclic load capacity, displacement, strain of concrete, strain in the primary reinforcement, and strain in the stirrup reinforcement.

Proposal for a novel technological damper system (TDS) for the retrofit of reinforced concrete frame structures

Considering the severe earthquakes that have occurred worldwide, it has been observed that even buildings which are constructed in compliance with the seismic regulations, have suffered heavy damage or collapsed. Similarly, in earthquake on February 6, 2023, in Kahramanmaraş, Turkey, many old and new structures were damaged or even collapsed. This situation has compelled researchers to focus on the most current and technological applications for earthquake protection. In the latest research topics, there has been a growing emphasis on the impact of new technological systems targeted at improving the seismic performance of structures constructed with reinforced concrete systems, given the notable occurrence of collapsed buildings with such structural systems in this earthquake. In this study, the developed Technological Damper System (TDS) was employed to enhance the earthquake performance of reinforced concrete structures. TDS is a versatile and adjustable friction-type damper. For this reason, two identical ½ scaled reinforced concrete frames were fabricated for the study, one representing a traditional structure as a reference frame (REF), and the other a frame with the TDS device. After applying quasi-static cyclic tests to the frames, the force-displacement, and force-rotation relationships, as well as energy dissipation capacities were determined for both frames. In addition, the damage conditions of the columns during the tests were assessed based on the plastic rotation limit conditions outlined in Turkish Building Earthquake Code (TBEC 2018). As a result, the frame retrofitted with the TDS device exhibited a significant increase in horizontal load-carrying capacity, ranging from 42.04% to 75%, when compared to the REF. Additionally, it was observed that energy consumption increased between 85% and 220%. The REF reached significant damage levels at 1% and 2% story drift ratios and an advanced damage state at about 3%, in accordance with TBEC 2018. Finally, the behavior of the frame retrofitted with TDS considerably improved according to REF and it reached a significant damage state at 3% story drift ratio.

Cyclic loading response of precast concrete beam-column connections with partially bonded draped prestressing tendon

An emulative precast concrete beam-column connection consists of prefabricated columns, T-shaped composite beams with partially bonded post-tensioned (PT) tendon, and cast-in-place (CIP) core region is proposed in this study. Experimental study was carried out to examine the hysteretic behavior of four full-scale beam-column connections under a high axial compression ratio (μ = 0.4). The specimens included a precast interior connection (PC1), a precast exterior connection (PC2), and two corresponding conventional CIP control specimens (RC1 and RC2). Performance assessment of the suggested connection was conducted by evaluating various factors, including failure mode, hysteresis curve, deformation, stiffness, and energy dissipation capacity. Test results revealed that all specimens fulfilled the design objective of strong column-weak beam with flexural failure showed at beams ends. In comparison to RC1, PC1 exhibited a 6.4 % increase in peak load-carrying capacity in the positive loading process and a 7.1 % decrease in the negative loading process. On the other hand, PC2 demonstrated approximately 11.9 % higher load-carrying capacity in the positive loading and a 2.0 % lower capacity in the negative loading when compared to RC2. The ductility coefficients of PC1 and PC2 was 3.39 and 2.64, respectively, which were slightly higher than that of RC1 and RC2 (3.01 and 2.43). All specimens exhibited good deformation restoring capacity and plump hysteretic loops, demonstrating satisfactory energy dissipation capacity. Overall, the proposed connection with partially bonded PT tendon showed comparable seismic performance with their CIP counterparts, indicated its promising potential for use in practical engineering applications.

Innovative Flexural Repair Technique of Pre-Damaged T-Beams Using Eco-Friendly Steel-Fibre-Reinforced Geopolymer Concrete

This paper presents an innovative flexural repair technique for pre-damaged reinforced concrete T-beams using eco-friendly steel-fibre-reinforced geopolymer concrete (SFRGPC). The study considers various parameters such as repair layer depth, location and configuration, and the use of additional reinforcement in one beam. The beams were preloaded to 50% of their ultimate flexural capacity. Extensive measurements were taken, including crack initiation and propagation, crack width, initial stiffness, load deflection, peak loads, ductility index, and strain values. The structural performance of the repaired T-beams under flexural loading was predicted using an analytical model. The repaired beams showed an increase in carrying capacity, stiffness, and ductility, but the failure mode was identical to the control samples. The study shows that SFRGPC shows great promise as a technique for not only repairing pre-damaged reinforced concrete beams but also for their strengthening. The best results were obtained with three-sided jackets with fibrous geopolymer concrete only, resulting in a load-carrying capacity increase of 25.8% compared to reference T-beams. The bonding between SFRGPC and existing concrete was effective, with no slippage or disintegration at the interface. The repaired beams’ structural behaviour and performance under flexural loads were successfully predicted using the analytical model, with a precision of about 98%.

ÇEVRİMSEL YÜKLER ALTINDA CFRP İLE GÜÇLENDİRİLMİŞ ÇELİK LEVHALI PERDELERDE ÇELİK LEVHA İLE CFRP ARASINDAKİ BİRLEŞİMİN AYRILMASININ DENEYSEL İNCELENMESİ

Steel plate shear walls, as an innovative lateral load resisting system, are widely used in the world. In this study, carbon fiber-reinforced polymer textile (CFRP) is used in order to increase load carrying capacity, ductility and energy dissipation of steel plate shear walls. A specimen of composite plate shear wall through epoxy bonding between two steel plates in a steel frame was prepared, and cyclic loading was applied. The finite element model of the steel plate shear wall without CFRP textile was prepared, and an in-plane static pushover analysis was conducted. The load-displacement curves obtained from the analysis of the model were compared with the results of the experimentally-obtained CFRP textile added specimen, and they were found to be in a good agreement. In conclusion, as a result of the addition of CFRP textile to the steel plate shear wall, it was observed that the carbon fiber reinforced polymer delaminated from the plate surface, and its contribution to the system behavior remained limited. Accordingly, it has been observed that in order to obtain the expected contribution, it is necessary to ensure that the steel plate and the textile must have full bonding and act as a composite material.

The Experimental and Theoretical Effect of Fire on the Structural Behavior of Laced Reinforced Concrete Deep Beams

A Laced Reinforced Concrete (LRC) structural element comprises continuously inclined shear reinforcement in the form of lacing that connects the longitudinal reinforcements on both faces of the structural element. This study conducted a theoretical investigation of LRC deep beams to predict their behavior after exposure to fire and high temperatures. Four simply supported reinforced concrete beams of 1500 mm, 200 mm, and 240 mm length, width, and depth, respectively, were considered. The specimens were identical in terms of compressive strength ( 40 MPa) and steel reinforcement details. The same laced steel reinforcement ratio of 0.0035 was used. Three specimens were burned at variable durations and steady-state temperatures (one hour at 500 °C and 600 °C, and two hours at 500 °C). The flexural behavior of the simply supported deep beams, subjected to the two concentric loads in the middle third of the beam, was investigated with ABAQUS software. The results showed that the laced reinforcement with an inclination of 45˚ improved the structural behavior of the deep beams, and the lacing resisted failure and extended the life of the model. The optimal structural response was observed for the specimens. The laced reinforcement improved the failure mode and converted it from shear to flexure-shear failure. The parametric study showed that the lacing bars remarkably improved the strength of the deep beams and they were not affected more by the steady-state temperature and duration. Furthermore, a greater increase in load-carrying capacity was associated with an increase in the flexural diameter of approximately 12 and 16 mm by approximately 24.77% and 87.61%, respectively, compared to the reference LRC deep beams.

Bilayer Couette flow over a profiled plate

AbstractThe shear–driven, bilayer flow of two immiscible liquids sandwiched between a moving planar and a stationary corrugated plate, in parallel alignment and under Stokes flow conditions, is explored. The motivation, partly inspired by biomimetic considerations, is the use of surface texturing/topography to reduce friction and wear while increasing load carrying capacity in lubrication problems. The starting point of the associated mathematical formulation is a variational principle which, in addition to the classical fluid mechanical field quantities, includes potential fields enabling an elegant reformulation of the dynamic condition at the interface separating the two layers. Two methods of solution are utilised: (i) an analytic one of the field equations, boundary and interface conditions by invoking the long–wave approximation; (ii) an exact semi–analytic one, obtained after transformation to complex variables and application of a spectral method. For validation and comparison purposes a FE formulation of the classical continuity and Navier–Stokes equations is solved for. Resulting streamline patterns, interface shapes and wall shear stresses are discussed.

Comparison of Encased Stone Column with Conventional Column for Varied Parameters through Experimental and Numerical Investigations

Installation of stone columns is a widely used stabilization method in improving the characteristics of soft clays. In this study, laboratory tests were conducted to understand the influence of column number, spacing and encasement on the load-carrying capacity of the modified soil. Unit cell concept is adopted for column diameters of 25.4 and 31.75 mm, one and two numbers of columns and spacings of 50, 70, and 90 mm under the conditions of with and without encasement. In addition to the laboratory study, finite element analysis was also done for similar parameters to understand the modified soil’s settlement characteristics and stress concentration ratio. Based on the analysis, it is understood that the load-carrying capacity increases with number of columns and spacing. Considering the influence of encasement, larger diameter columns showed a more significant increase in the load-carrying capacity when compared to the smaller diameter columns.

Crossed helical gears—simulative studies and experimental results on non-involute geometries

Crossed helical gear units generally consist of a steel worm and a plastic helical gear with an axis crossing angle. Due to the high transmission ratio in a small installation space, they are used in auxiliary and actuating gears such as in window regulators, assembly lines, household appliances and positioning tasks. This paper deals with a calculation approach for crossed helical gears to include non-involute flank geometries for new and optimized gearboxes. The geometry derivation for general flank contours based on a polynomial and extends the geometric possibilities beyond the special case of the involute form. The use of principal curvatures and principal curvature directions to describe freely curved surface geometries enables the calculation of flank pressures, efficiency and sliding paths in the entire contact area. Previous studies confirmed the advantages in the mentioned load characteristics for geometries deviating from the involute. Furthermore, parameter studies show the influences of the individual design parameters and demonstrate the effects on operating behavior, with those a design recommendation for crossed helical gear units with general flank geometries can be created. ZC and ZC‑S geometries are used as calculation examples. With regard to the use of these new geometries in applications, manufacturing is a crucial aspect. Grinding disc parameters as well as a three-roll size to control the worm manufacturing for general flank geometries are necessary and described below. In addition to the theoretical calculation, a ZC crossed helical gear geometry was designed, manufactured and compared to a ZI reference gear in test rigs. This confirmed the advantages in load-carrying capacity and efficiency increase resulting from the calculation and proved the benefits.

Numerical analysis of hydromagnetic micropolar squeezing flow lubricated between porous elliptical plates

An attempt is made to analyze the effects of micropolar fluid squeezing film implementation between porous elliptical plates under the application of an external magnetic field. The appropriate improved hydromagnetic Reynolds equation governing the pressure distribution is acquired. The Reynolds equation is solved for lubrication features such as pressure distribution, load-carrying capacity and time-height relationships. It is noticed that a micropolar lubricant with a magnetic field may considerably impart a much-appreciated increase in load-carrying capacity, pressure distribution and response time compared to the classical case. Nevertheless, it is found that, as with the magnetic field, the larger values of the fluid gap number and the coupling number increase lubrication characteristics. Also, it is found that such a bearing cannot support a large number of lubrication characteristics because of the pores on the main path of fluid flow.

Fabrication and characterizations of glass fiber-reinforced functional leaf spring composites with or without microcapsule-based dicyclopentadiene as self-healing agent for automobile industrial applications: comparative analysis

This study described a critical review of the biological system of self-curing agents and catalysts in which damage triggers an automatic healing response. In the first phase, a glass fiber-reinforced composite (GFRC) mono-leaf spring was prepared, which is made of glass fiber with a cement-based metal matrix. GFRC was further embedded with a microcapsule-based self-healing agent dicyclopentadiene (DCPD) that prevents sudden breakdown/failure of automobile suspension components resulting in micro-cracks produced in the material due to constant load application. In this paper, GFRC mono leaf spring samples were prepared with and without a healing agent under three different categories of varying thicknesses 20, 30, and 40 mm. In the second phase, the load-carrying capacity of all the samples was investigated and found a continuous increase in load-carrying capacity. Percentage increase in load carrying capacity before the time break was 1.09%, 1.42%, and 1.08% followed by time break of 05 min was 24.24%, 17.67%, and 21.67% respectively. It was clearly identified from the results that the addition of microcapsule-based healing substituents increases the load-carrying capacity of GFRC mono-leaf spring and avoids sudden fracture.

Performance analysis of journal bearing having surface waviness operating under misaligned condition

In this present study, the effect of surface waviness on the performance of journal bearing operating in misaligned conditions has been investigated. The journal’s misaligned conditions in the present analysis are taken about the circumferential, the axial, and both axes. For computing the pressure of lubricant inside the bearing, the finite element method has been applied to solve the Reynolds equation and thus static parameters are obtained. The static parameters, that is, load carrying capacity and coefficient of friction are evaluated at different waviness variables and are compared with misaligned journal bearing without surface waviness. It is observed that misalignment considered in both axes has the most severe effect on static performance parameters as compared to misalignment only in the circumferential or axial axis. With the increase in circumferential waviness number up to n = 5, the load-carrying capacity increases, and the coefficient of friction decreases under high eccentricity ratios. Change in waviness amplitude also impacts the bearing performance. Axial waviness always deteriorates the bearing performance. Combined waviness increases the load carrying capacity and decreases the coefficient of friction when circumferential waviness number n = 5 and axial waviness number m = 2. The highest performance enhancement ratio is attained at an eccentricity ratio of 0.8 with a circumferential waviness number n of 5, axial waviness number m of 2, and dimensionless waviness amplitude [Formula: see text] of 0.075.

Numerical Analysis of a Dual-Layer Geosynthetic-Encased Stone Column Installed in Soft Soil

Stone columns are being used to reduce soft soil settlement and increase load-carrying capacity. Since there is inadequate lateral support from the local native soil, soft soil undergoes excessive settlement under vertical loading. This issue is effectively resolved by suitably encasing stone column material by geosynthetic with significant axial stiffness, which provides the required additional confinement reported in the literature. In the current study, an effort has been made to examine the load settlement behaviour of the dual-layered geosynthetic-encased stone column (DL-GESC) under vertical loading. In order to simulate the behaviour of stone column-reinforced soft soil, a FEM analysis was performed using PLAXIS-3D and three-dimensional (3D) models made utilising the unit cell idealisation technique for a single column. The stone column diameter, spacing to diameter (s/d) ratio, and encasement layers were varied to determine their influence on load-settling behaviour. The vertical load-carrying capacity of the ground was significantly improved when an additional layer of geosynthetic encasement was inserted into the stone column as compared to SL-GESC. Improvement of 15–25% was observed for the analysis of a single column installed in soft clay, according to the result obtained. Improvement ratios have been discussed in detail for various encasement conditions.

Seismic Upgradation of RC Beams Strengthened with Externally Bonded Spent Catalyst Based Ferrocement Laminates

Globally, since there are more systems of civil infrastructure, there are also more degraded buildings and structures. If upgrading or strengthening is a practical option, complete replacement is likely to be an escalating financial burden and may be a waste of natural resources. It is necessary to repair or strengthen a number of reinforced concrete buildings and structures in order to boost their load-bearing capabilities or improve their ductility under seismic stress. Additionally, due to changes in service circumstances, a structure might need to be modified to reduce deflections or manage cracking. Strengthening may be preferable to limiting usage, capping applied loads, and regularly inspecting the structure rather than removing the existing structure or part and building a new one. This study aims to examine the flexural, shear, and combined effect of flexural and shear behavior of reinforced concrete (RC) beams strengthened with externally bonded spent catalyst-based ferrocement laminates and compare them to the control beams (unstrengthened) under two-point loading conditions. This study involves researching laminates with various spent catalyst doses, such as 3, 6, 9, and 12%, in an effort to determine the best amounts that will improve the structural performance of ferrocement laminates. Twelve spent catalyst-based ferrocement laminates measuring 500(L) × 125(B) × 20 mm (thickness) with 3% volume fraction of meshes each were cast and tested in the lab as part of the preliminary investigation. For repeatability, three laminates per case were employed. Eight numbers of under-reinforced RC beams measuring 75(L) × 100(B) × 150(D) mm were cast for the main study; six numbers were strengthened with optimized spent catalyst-based ferrocement laminates bonded with flexible epoxy systems at the tension zone, shear zone, and combination of tension and shear zone. Two of the beams were cast as control specimens. The beams were then evaluated using a Universal Testing Machine (UTM) with a 1000 kN capacity under two-point loading conditions. As a result, the strength, yield load, ultimate load, stiffness, ductility, and related failure modes of all tested beams' flexural and shear performances were examined. According to a preliminary analysis of laminates made of spent catalyst, the dosage of 9% provides good flexural strength in comparison to other doses. In comparison to the strengthened beam, the control beam's initial cracks appeared earlier. In comparison to the control beam, the strengthened beam has an increase in load-carrying capacity of 18% for flexure, 16% for shear, and 30% for the combined impact of flexure and shear. In comparison to the control beam, the deflection of the strengthened beam was decreased by close to 20 to 40% for flexure, 10 to 30% for shear, and 15 to 20% for the combined effects of flexure and shear at the same load level. In relation to control beams, the ductility also improved up to 30% for flexure, 25% for shear, and 25% for the combined impact of flexure and shear. Similar to this, the retrofitted beam is stiffer than the control beam by approximately 40% for flexure, 48% for shear, and 30% for the combined effect of flexure and shear. Theoretical formulation by section analysis is also derived and it gives close agreement with control and strengthened beams. The flexural and shear strengthening of the RC beam retrofitting system is effectively increased by using spent catalyst-based ferrocement laminates. No beam showed signs of premature and brittle failure. According to the test findings, it can be said that spent catalyst-based ferrocement reinforced beams perform better in every way than control beams. Doi: 10.28991/HIJ-2023-04-01-013 Full Text: PDF

Experimental Investigation of Effect of L-Profile Hybrid Aluminium/GFRP to the Axial and Lateral Characteristic.

The current study investigates the effect of a hybrid L-profile aluminium/glass-fiber-reinforced polymer stacking sequence under axial and lateral compression loads. Four stacking sequences are studied: aluminium (A)-glass-fiber (GF)-AGF, GFA, GFAGF, and AGFA. In the axial compression test, the aluminium/GFRP hybrid tends to crush in a more progressive and stable failure than the net aluminium and net GFRP specimens, with a relatively more stable load-carrying capacity throughout the experimental tests. The AGF stacking sequence was second, with an energy absorption of 145.31 kJ, following AGFA at 157.19 kJ. The load-carrying capacity of AGFA was the highest, with an average peak crushing force of 24.59 kN. The second-highest peak crushing force, 14.94 kN, was achieved by GFAGF. The highest amount of energy absorption, 157.19 J, was achieved by the AGFA specimen. The lateral compression test showed a significant increase in load-carrying and energy absorption capacity in the aluminium/GFRP hybrid specimens compared to the net GFRP specimens. AGF had the highest energy absorption with 10.41 J, followed by AGFA with 9.49 J. AGF also had the highest peak crushing force with 2.98 kN, followed by AGFA with 2.16 kN. The most crashworthy stacking sequence among the four variations tested in this experimental research was the AGF stacking sequence because of its great load-carrying capacity, energy absorption, and specific energy absorption in axial and lateral loading. The study provides greater insight into the failure of hybrid composite laminates under lateral and axial compression.

Study of Application of Fiber Reinforced Concrete in Anchorage Zone

In the case of post-tensioned or geotechnical structures, the anchorage zone is considered a critical part of the design and construction process. Generally, the failure of the anchorage zone is one of the most common problems. High-bearing stresses create significant transverse tension. For these reasons, conventional reinforcement, usually in the form of closed stirrups, must be designed. The presented analysis is focused on the possible increase of load-carrying capacity of the anchorage zone with steel fiber-reinforced concrete. Three types of specimens were analyzed. The first type of specimen represented the anchorage zone made from standard reinforced concrete. The second and third series of specimens were designed from fiber-reinforced concrete with two different volumes of steel fibers added into the anchorage zone. The parameters used in the numerical analysis of the anchorage zone were experimentally determined on a set of beam specimens. In the analysis, the anchorage zone was loaded by a node force applied on a steel load distribution plate placed on the top edge of the bloc. The performed numerical study suggests that the load-bearing capacity can be increased by adding fiber-reinforced concrete with a higher volume of fiber (Dramix 3D 55/30, volume of fiber of 110 kg/m3) into the vicinity of the anchorage plate.

Influence of Haunch Geometry and Additional Steel Reinforcement on Load Carrying Capacity of Reinforced Concrete Box Culvert

The culverts are used to safely convey water under railways, highways, and overpasses. They are utilized in drainage areas or water channels and in areas where the bearing capacity of soil is low. The design and construction of this crucial infrastructure need to be improved to meet contemporary demands of reliability and affordability. Precast reinforced box culverts are popular alternatives as they ensure strength, durability, rigidity, and economy. This research seeks to develop an effective and affordable design improvement procedure for a precast box culvert using modern numerical tools. The Finite Element Method (FEM) based approach is used in studying the effects of haunch geometry and additional steel reinforcement on the load-bearing capacity of box culverts. A conventional box culvert is analyzed to create the numerical models in the Abaqus FEM code and to investigate the load-bearing capacity of culverts with an expanded span. The outcomes of the study reveal the critical places for stress concentration as well as the location of maximum damage. It is found that haunch geometry and additional reinforcement at these critical places significantly affect the load-carrying capacity of a culvert. From the comparison of capacity curves of models with and without haunches and diagonal reinforcement, it is found that a 25% increase in load-carrying capacity is achievable with the recommended changes. The proposed design improvement technique can be employed for the cost-effective and safe design of a concrete box culvert with larger span lengths and high water-flowing capacities. The findings of this study are expected to assist practitioners in strength enhancement tasks of box culverts for increased structural stability and drainage efficiency.

Flexural performance of high-strength lightweight concrete beams made with hybrid fibers

This paper reports on the flexural response of lightweight high strength concrete beams, (LWHSC) reinforced with different combinations of discrete, discontinuous and randomly distributed steel, crimped polypropylene and recycled plastic fibers. All the LWHSC beams tested failed in a typical flexural failure mode, in which flexural vertical cracks appeared within the constant moment zone. Analysis of the test results indicated that the fiber reinforced LWHSC beams exhibited significant increase in load carrying capacity, flexural toughness and ductility indices compared to control LWHSC beams without fibers. Among all the beams tested, the ones reinforced with 0.5% of 60 mm long steel fibers and 0.25% of crimped polypropylene fibers exhibited the largest increase, about 18% in load carrying capacity and flexural toughness compared to control beam specimens without fibers. While, the beams reinforced with 0.5% (50/50 blend) of short steel fibers (30 mm and 60 mm long), and 0.25% of recycled plastic fibers outperformed the flexural toughness of similar beams containing equal content of steel fibers and 0.25% of crimped polypropylene fibers by about 6%. Furthermore, test results indicated that an eco-friendly locally produced recycled plastic fibers could be successfully used for enhancing the flexural performance of LWC beams without compromising their load carrying capacity. Moreover, finite element software ABAQUS was used for predicting numerically the flexural response and crack progression of the beams investigated. The numerical predictions compare fairly well with the experimental test results

Experimental Investigation on the Axial Compressive Behaviour of Cold-Formed Steel-Concrete Composite Columns Infilled with Various Types of Fibre-Reinforced Concrete

The exceptional structural strength and low cost of steel-concrete composite columns make them a popular choice for civil engineering structures. Numerous forms of composite columns, including steel tubes filled with concrete, have been produced recently in response to various construction situations. Cold-formed steel tubular columns with concrete filling have higher strength and ductility due to their capacity to withstand inner buckling and postpone outward buckling. The objective of this research is to determine the ductile and strength performance of composite columns containing various forms of fibre-reinforced concrete when subjected to axial compression. Several different kinds of fibre-reinforced concrete (FRC) are employed as additives in hollow steel columns, including steel FRC, carbon FRC, glass FRC, coir FRC, jute FRC, and sisal FRC. Axial compression tests were performed on 24 columns, including three hollow steel columns and 21 composite columns. Three distinct slenderness ratios were developed and used. Axial bearing capacity, compressive stress-strain curves, ductility, peak strain, axial shortening, and toughness were among the topics covered by the axial compression test. Experimental findings demonstrated that all conventional composite columns experienced failure through overall buckling, Local buckling and crushing of concrete infill, which was transformed into more ductile failure using fibre-reinforced concrete infills. The test results revealed that fibre-reinforced concrete-infilled steel columns outperformed conventional composite columns in terms of strength, ductility, and energy absorption capacity. The percentage increase in load-carrying capacity was observed as 203.88%, 193.48% and 190.03% when compared to hollow cold-formed steel tubular columns in medium, short and stub columns, respectively. Under assessment of stub, short, and medium columns, the load-strain plots demonstrated that the steel fibre-reinforced concrete in-filled columns performed well in terms of ductility. Localized buckling and crushing of the concrete infill caused the composite columns with low slenderness ratios to fail. In contrast, concrete-filled steel tube columns with higher slenderness ratios showed column failure through the overall buckling of the composite column.